PSIO 121 5th Edition Lecture 32Outline of Last Lecture AUTONOMIC NERVOUS SYSTEM: SYMPATHETIC DIVISIONOutline of Current Lecture I. AUTONOMIC NERVOUS SYSTEM: PARASYMPATHETIC DIVISIONII. Cranial NervesIII. PSNSIV. Syncope Current Lecture1. Differentiate between the parasympathetic and sympathetic nervous systems in terms of anatomy, neurotransmitters used, and the effects produced by each system.2. Describe syncope and its relationship to the parasympathetic nervous system.Cranial Nerves:1. Oculomotor(III) – mixed cranial nerve responsible for eye ball movement stimulates the lacrimal gland2. Facial (VII) – mixed cranial nerve stimulates salivation3. Glossopharyngeal (IX) – mixed cranial nerve involved in swallowing and salivation4. Vagus (X) – mixed cranial nerve; carries 80% of parasympathetic outflow to heart,airways, liver, gallbladder, stomach, small intestine and part of large intestine. Cranial Portion:1. Preganglionic neurons found in ponds or medulla2. Information carried by 4 cranial nerves – III, VII, IX, X3. 80% of PSNS information carried by Vagus (X)Sacral Portion:1. Preganglionic neurons in sacral region (S2-S4) exit via pelvic nervesPSNS Ganglia :- cranial preganglionic neurons synapse at one of four ganglia - 1. Ciliary- 2. Pterygopalatine- 3. Submandibular- 4. OticCholinergic Receptors:- respond to ACh1. Nicotinic receptors – found on sympathetic and parasympathetic cell bodies and dendrites of postganglionic neurons (within ganglion) – can only generate excitatory post- synaptic potentials (EPSP)2. Muscarinic receptors – found on membrane of target tissues innervated by parasympathetic postganglionic axons – can generate both EPSP and inhibitory post- synaptic potentials (IPSP) Cholinergic Receptors (PSNS)“Rest and Digest”Goal: Promote digestion of food and the absorption of nutrients- Salivation- Lacrimation- Urination- DefecationSpecific Responses to PSNS- Increased digestive enzyme/hormone secretion- Increased smooth muscle activity of the GI tract- Constriction of pupils for near vision- Decreased heart rate, contractility, blood pressure- Contraction of muscular wall of bladder and intestine promotes urination/defecation- Increased secretion of the lacrimal glandsClinical Application: SyncopeSyncope = fainting = vasovagal reaction- transient loss of consciousness resulting from an insufficient suppy of oxygen to the brain- insufficient cerebral perfusion from hypotension because of failure of ANS to maintain blood pressure- syncope can be avoided by laying down in supine position, elevating feet, contracting leg and arm muscles to bring more blood back to the heart and increase circulation of blood to the
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